Fosfatos en la industria cárnica

The relationship between vehicle speed, pedestrian accidents, and the severity of injury was reviewed by Leaf and Preusser, who also analysed accident data sets in the USA. For example, they analysed data from single-vehicle pedestrian accidents in Florida between 1993 and 1996, and found that older people were more easily injured at all speeds. Even below 20mph, the risk of fatality was three times greater for those over 65. From 21–30mph, those over 45 had more than double the risk of fatality of younger adults, and the risk was about five times greater for those over 65. Over 45mph, older people were found to die in about 60% of accidents. Those over 65 had higher injury rates than younger people at all speeds. Savill and Chinn (1993) found that the most common suggestion made by older and disabled

pedestrians in an English town was to reduce the speed or volume of traffic.

Speed increases the energy in a collision, and reducing vehicle speed should reduce the harm done by accidents (Oxley et al., 2001). Moreover, if cars are moving more slowly, drivers will be operating with margins for error that better match their true capacity to respond, and pedestrians will have more time to detect and respond to their presence. This should reduce the number of accidents occurring, and should particularly help older road users who react more slowly. A study of pedestrian fatalities in Adelaide estimated that a 5km/h vehicle speed reduction would spare 30% of pedestrian fatalities (McLean et al., 1994). The link between vehicle speed and pedestrian accident severity in London was noted by Hillman and Whalley (1979). Two recent reports provide detailed information on possible interventions to reduce vehicle speed. DUMAS (1998) reviewed modifications to the road

environment that are used to slow vehicles in Europe. Leaf and Preusser (1999) reviewed strategies to reduce vehicle speed, including changes to the road

environment, education, and enforcement. In the remainder of this subsection we briefly give some examples highlighted in recent reviews.

Research in the UK has shown that injury accidents in 20mph areas are reduced by 64% in town centres and 68% in residential areas, with reductions in mean vehicle speed of 11.5mph (from 32.0mph) and 12.1mph (from 35.6mph), respectively (PROMISING, 2001). Traffic volume was also reduced. On rural main roads such schemes achieved smaller reductions in speed and traffic volume, and accidents fell by 53%. Vis and Kaal (1993; cited in Hummel, 1999) examined 151 30km/h zones in the Netherlands, and found accident reductions of 2213%, but pedestrian

accident rates were not reported separately. Kraay and Dijkstra (1989; cited in Hummel, 1999) reported injury accident reductions in 30km/h zones of up to 70%, and 20% in neighbouring main roads. Dijkstra and Bos (1997) reported mixed results, with not all sites showing accident reduction.

Oxley et al. (2002) argued that area-wide speed interventions are more effective than blackspot targeting, and described an intervention on an arterial route in a commercial area of Melbourne combining measures such as speed limit signs, painted median strips, and raised crosswalks. Vehicle speeds did fall, but for reasons that were unclear, bigger speed reductions occurred at the control site. Elvik (2001) reported a careful meta-analysis of 33 evaluations of area-wide traffic calming, and concluded that injury accidents are, on average, reduced by 25% on residential streets, and by 10% on main roads. In general, the data suggest that speed restriction reduces accidents overall, as one would expect. Because older people tend to have their accidents close to home, are especially vulnerable to impact, and are slower themselves, they should particularly benefit from this type of intervention. Speed reduction in residential areas and shopping streets was recommended as a measure to benefit older pedestrians by the OECD (1986).

The Dutch model of ‘‘Woonerven’’ (pedestrian precedence residential areas) has been adopted in several European countries. In these areas, the pedestrian has priority. The effectiveness of such schemes varies between countries, partly as a function of enforcement (PROMISING, 2001). Plowden and Hillman (2001) reviewed a number of schemes in residential areas to reduce conflict between

pedestrians and vehicles. Some were evaluated in terms of speed reduction, others in terms of accident rates. In general, they found that such measures often did reduce vehicle speeds or accidents. Schemes that focus on the design of residential areas will particularly benefit older people whose accident involvement tends to be on familiar streets close to home. Some piloting of ‘‘living street’’ projects is underway in various towns and cities in the UK, where regulations are being prepared by the DTLR, and the Institute of Highway Incorporated Engineers is expected to publish guidelines in 2002. Similar ideas were implemented in the UK as ‘‘Play Streets’’ in the 1930s, and were termed ‘‘environmental areas’’ in the Buchanan Report (Cohen and Preston, 1968). An existing publication provides a detailed illustration of traffic- calming measures at sites in England, together with a commentary on their relative success (County Surveyors Society, 1994). In most cases, intervention successfully reduced speed and was judged to have reduced the likelihood of pedestrian

accidents.

The safety benefits of pedestrianisation in town centres are widely recognised. The rebuilt centres of cities like Coventry have been designed in part around this

principle. York has demonstrated that pedestrianisation can lead to a more rapid rate of casualty reduction for all road users. and that there can be an economic benefit to commercial property in ‘‘footstreets’’ (Transport Committee, 1996).

Taylor and Tight (1996) carried out surveys during traffic-calming interventions at 10 sites in Scotland. They found that the larger local people felt the speed reduction had been, the more they were prepared to walk or cycle. High vehicle speed causes accidents, increases injuries, and may deter walking. Older people are especially vulnerable to injury (section 1.3.4) and tend to express particular concern about traffic speed (Carp, 1971; Savill and Chinn, 1993).